Finally got around to installing my Roto-fab yesterday and found this where the stock airbox connects to the throttle body. The dealership replaced the lifters and pistons/rings a couple months ago. I had noticed a bit of a rough idle and my mpg were down a little bit, now i know why. After installing the Roto-fab and cleaning the MAF she is idling smooth as can be and mpg is up.
Anyone on the fence about doing these simple mods...DO IT! With just the Roto-fab and Cortex it is a completely different beast.